The present invention relates to a novel apparatus for producing aluminum strips which are used as base materials of aluminum foils.
Broadly, there are two types of known processes for producing aluminum foils. In one of these two types of process, as shown in FIG. 2, an aluminum web is first subjected to hot rough rolling conducted by a hot roughing mill A composed of a hot roughing mill uncoiler 1, a hot roughing roll stand 2 and a hot roughing coiler 3. The roughly rolled aluminum web is then subjected to cold finish rolling effected by a cold finish rolling mill B composed of a cold finish roll uncoiler 4, a cold finish rolling stand 5 and a cold finish rolling coiler 6. The aluminum web after the finish rolling is then annealed in an annealing equipment C having an annealing furnace 7 and the thus annealed web having a substantial width is slit into strips by means of a slitting equipment D composed of an uncoiler 8, a multislitter 9 and a coiler 10, whereby aluminum strips as the base material of aluminum foils are obtained in the form of coils.
In the other type of the known processes, as shown in FIG. 3, the aluminum web is first roughly rolled by a hot roughing mill A followed by cold finish rolling conducted by a cold finish rolling mill B. The cold-rolled aluminum web having a substantial width is then slit into strips by a slitting equipment D and the thus obtained strips are annealed through an annealing equipment C having an annealing furnace, whereby aluminum strips as the base material of aluminum foils are obtained.
These two types of known processes, however, suffer from the following disadvantages. Namely, in the process explained in connection with FIG. 2 in which the aluminum web is slit into strips after annealing, the aluminum web when slit exhibits a high level of ductility on the order of 3 to 7 kg/mm.sup.2 in terms of tensile strength, so that widthwise edges of each strip obtained through the slitting tend to exhibit thicknesswise protrusion or burrs 14 (see FIG. 6) as a result of contact between these edges and side surfaces of the slitting blades or separators which are adapted for guiding the strips after the slitting. In consequence, each strip coiled on the coiler exhibits a bell-like form with both widthwise ends expanded radially outwardly, as indicated at 22 in FIG. 4. Various attempts have been made to obviate this problem. For instance, an attempt has been made to employ an ironing roll downstream of the slitter and adapted for forcibly depressing the protrusions on both widthwise ends of the strip. In another attempt, the distance between adjacent slitting blades are increased so as to suppress any tendency for each strip to be bent along both widthwise ends thereof, which tendency being often observed when the distance between adjacent blades is small. In still another attempt, the strip is formed such that, as shown in FIG. 5, the burrs project beyond the desired strip width w to be obtained. All these attempts, however, are still unsuccessful.
On the other hand, the second type of the known process features that the aluminum material is annealed after it is slit into a plurality of strips. In this case, almost no bends or burrs are formed on both widthwise ends of each strip, because the aluminum web immediately after cold rolling exhibits a high level of hardness when slit. In this case, however, a number of coiled strips are annealed so that the scale of the annealing equipment has to be increased as compared with the method explained in connection with FIG. 2, with the result that the installation cost is raised and the working time is prolonged due to necessity for handling of a number of strip coils.